Tear-down in progress..

Am I right in assuming that during re-assembly you should put the ring across more than one piece if possible? Like, as an example, my seca's motor output is a shaft, driven by a helical gear inside the gearbox. (Is that the mysterious "middle gear"? I can't find it labeled clearly in any of my paperwork). There is one of those half rings that goes where the gear shaft seats properly. Channel on both the top and bottom case halves. We reinstalled it vertically, so that the clip is in the groove on the top and bottom case halves.

 

Salvation! Managed to remove the three screws retaining the starter clutch asssembly. The chain guide is now exposed.. or what little of it is left, anyway.. Good gawd...

So while I'm in here, I seem to recall that these bikes' starter clutches are a problem area. Anything I should look at before I order the parts I need? Or do I not even need to look, just go ahead and replace something?

 

Crewwolfy,

Can you please post pics of the chain guide assembly, and also your opinion on whether or not it would be accessible through the oil sump (if the bike were flipped onto it's handlebars)? Chacal was theorizing that this might be possible, with the use of extensions and swivel sockets. Your assistance would be invaluable in researching this.

Thanks.

 

Sure thing.


Here's a picture of the top half of the engine, where all the goodies are. The starter chain is lifted over to the left side. As you can see, only half of the chain guide remains. (No, I will not be using that toothbrush on my teeth ever again..)


The red circles indicate the connection points for the guide. I do know that it'd be impossible to replace the guide with the starter chain in place. If you can do it without splitting the cases, the starter clutch would have to be displaced. I don't know if I'd want to try that with the cases intact.

I'll have a better idea on whether or not you can replace the guide without splitting the cases when I reassemble, now that I know what to look for.

 

Dude, that is awesome. I finally have an image of what's going on. Yeah...I don't really see how this can be done through the oil sump but do look into it for us.

 

Crewwolfy, I had to remove the crank to replace mine. Good opportunity to check the condition of the crank bearings.
Hint: DON'T misplace the bearings upon removal (small bit of experience, cost me two weeks). Be sure to use assembly grease upon re-installation.

 

IF.. you ever get the cases split you MUST replace the Primary Chain.
IF .. you want to ride the bike for a bit after reassembly.
Replacement requires the Crank out of the Case, with Rods removed. Pretty well as far as one can dissasemble the engine unit
You realise the Primary chain stretching took out it's chain guide??
Instant "test' for a primary chain condition is to put it on a table where the chain's to row ..must not.. sag enough to touch the bottom. row
Not cheap either as it's a "captive' part just to add insult to injury (means it's only from the dealer) It's a V stupid design.. period, mercifully a long obsolete one.
Rings are not as often needing replacement as the primary chain., if that helps you.

 

This is the first I'm hearing about having to replace the primary chain. Why would splitting the cases require you to replace the chain? I understand the idea that the chain stretching broke the guide, but not the case-splitting part.

 

Crew.......it actually still migh be possible to remove the chain guide even with the chain in place. The replacement GUIDE only has two (2) bolt tabs, one on each end; the center one is no longer there.

The rear mounting bolt is pretty much a straight shot down with the oil pan removed (engine together), all you'd need is a long extension on a ratchet. It's the front bolt that's questionable.......

If you haven't already torn down your bottom case, it would be an invaluable experiment if you could set the bottom case----with all the pieces still in place-----back onto the top case, and with the oil sump pan removed, let's see if there is any way that the front bolt could be reached? If necessary, the alternator rotor/starter drive clutch shaft could be removed; that's actually pretty simple to do.

I'm pretty sure that once the front and rear (and, in the case of an original chain guide, the center mounting bolt, too) are removed, the guide can be snaked out towards the rear.....it's a pretty flexible piece.

Again, all I'm trying to establish is that if it is at all possible to do this replacement with the engine still in the bike. As the years (and miles) go by, this is the most common "wear item" inside the engine case that needs perodic replacement, and if it is at all possible to acoomplish this without having to do an engine teardown, then that would be very helpful to many owners who just don't want to or feel confident to remove th engine and split cases.

I know that someone figured out how to change the starter clutch pins without taking th engine apart, as well as changing the shift fork dogs from the bottom of the engine.


BTW, the starter clutch pins, caps, and springs should be replaced, and the condition of the housing should be inspected carefully for any cracks. I believe that Pollock has posted a great picture of what to look for on it:

http://www.xjbikes.com/Forums/viewtopic ... lutch.html

 

Since it's not a true primary chain (doesn't drive the transmission only the alternator) does it need replacement? Doesn't the guide just fail from rubber deterioration?

 

Yeah..what Len said.

I didn't know that middle bolt tab wasn't there anymore.

 

Ok, so here's the dealio. Keep in mind this is an 82 XJ650 Seca (non-YICS). No idea if it pertains to other models..

Here's an image of the chain guide.

The guide does have three bolt tabs. So removing/replacing all three is necessary.

Overall shot, with the cases together, through the oil pan.

I actually just realized that this doesn't include the middle gear assembly, which is sitting on a pizza box (not pictured). However, looking at where it goes, it shouldn't interfere.

Rear location.

Out of the range of the camera, but reachable. I actually went through the starter clutch hole, as I didn't have an adequate extender for the wrench.

Center location.

Without splitting the cases, you'll need a long extender for this bolt, but you can reach it through the oil pan. All these bolts are coated with Loctite, however, so be forewarned. Not difficult if you have plenty of room.

Front location.

And now for the bad news. I have no picture of this bolt through the oil pan because, well, you can't see it. In theory, I suppose it is possible to remove, but you would need a very flexible extender. Or maybe that thing Tom Cruise uses in Mission Impossible. If you do remove it, it's likely to fall into the head along the chain. And I have no idea how you'd manage to screw it back into place.

So there you have it. While I am no expert, I don't see how one could replace the chain guide on this engine without splitting the cases. I personally don't think it's [realistically] possible.

That being said, I really didn't find splitting the cases to be all that difficult. Seems like a very daunting task, but it was actually quite simple. As far as putting it all back together... Well, hopefully I can answer that in a couple weeks.

Organization is key.

(Insert MasterCard commercial with cardboard box and ziplok bags..)

I'll be ordering parts from Chacal, so she'll be gutted for at least another week. Let me know if anyone needs any shots in particular.

 

I was thinking that with two 90-degree swivels on an extension, and with the crank throw rotated out of the way (over by where the front bolt is), that maybe you could get to it through the large opening on the right side?

I think if you used a magnetic adapter on the socket your risk of losing the bolt (and of re-installing it) might be minimal. Yes, they are lock-tited in place but they do not use a lock of torque during installation. Perhaps one of those really funky-offset wrenches like they use on cars to loosen the distributor lock-down bolt (to loosen the distributor so you can adjust the timing)?

 

I tried rotating the crank for a better angle, to no avail. I'll try some more in the near future. Don't want to get too dirty tonight.

 

Okay, thanks!

 

Since it's not a true primary chain (doesn't drive the transmission only the alternator) does it need replacement? Doesn't the guide just fail from rubber deterioration?

 

David3aces, Yup. I've not seen a failure involving the HyVo chain yet. It lives in the oil bath and unless you run the bike out of oil, should last as long as the engine.

 

Great pics and info. I saw (I think earlier in this thread) a mention that the chain stretches and wipes out the guide. Comments?

 

I believe that's the HyVo chain Robert's talking about.

 

oops missed that sorry. I'm easily confused :wink: